56 posts from February 2014

February 28, 2014

1:45 PM - the entire WAVE 3 New viewing area is now under the WINTER STORM WATCH Sunday morning though Monday evening.

1:55 PM - WAVE 3 Weather on Facebook is the hub of all things weather. Stay up to date on the approaching winter storm by visiting and liking our page.

2:00 PM - call with the local media for scientific discussion of upcoming winter storm

2:25 PM - media call wrapping up... on to emergency managers.

2:28 PM - if you're looking for exact answers of who sees what... you likely won't get what you're looking for this far in advance. Models still have a huge spread. It's going to be a big deal... narrowing down who sees freezing rain, sleet & snow and each amount is not very clear at this point in the game.

2:30PM - LIVE UPDATES WILL BEGIN - scheduled start time of the call with emergency managers, etc. John Gordon, Meteorologist In Charge at the National Weather Service leads the call.

2:45 PM - Ice Storm Warning (greater than quarter inch of ice) - don't anticipate one being issued, because there will be many types of winter weather... freezing rain, sleet & snow. Some places will get a significant amount of ice.

2:46 PM - Evansville could get some stuff before Louisville... travel should return to Louisville Saturday night.

2:46 PM - City of Jeffersonville... precipitation will start before daybreak on Sunday. The worst part of the storm 50% snow & 50% ice (refined more Saturday) from 3PM Sunday to 3AM Monday.

WINTER STORM WATCH has been issued in advance of a possible Winter storm on Sunday. At this time, the National Weather Service has included all of our Southern IN counties, but I fully expect the watch to be pushed farther South during the next update. We'll be watching this closely as it has the potential to create big problems Sunday evening into Monday. At this point, I want to steer clear of specifics. This storm is still 2 days away and is VERY complicated. This blog is meant to bring awareness to the fact that a storm system is headed this way.

TODAY: low 40s, increasing clouds.

TONIGHT: 32, mostly cloudy, small chance for a wintry mix

SATURDAY: 51, early morning rain

SUNDAY: low 30s, early morning rain transitions to freezing rain. How far South the freezing rain line sets up will be crucial in determining ice accumulation. There will be periods of ice, sleet, and rain throuhgout the day Sunday with the storm peaking Sunday evening into Monday. A widespread area of freezing rain is looking likely Sunday night before transitioning to snow by the morning rush on Monday. A few inches of snow will be possible for some of us after ice accumulation Sunday. At this point, freezing rain totals could exceed .25" in some spots...definitely worth paying VERY close attention to. Stay tuned to wave 3 news and wave3.com for the latest updates.

February 27, 2014

All the midday data is in. Threat for a winter storm in our region remains on the table for Sunday-Monday.

As mentioned in the video, this looks to be 2 waves. First one looks like rain for many during daylight Sunday with freezing rain far north.

The second one (main low) moves in Sunday night/Monday. That is the one to watch for the heaviest amounts of precipitation. Which such decent moisture, the type is crucial for impact. All we can say with confidence at this point is that northern sections run the highest threat right now for freezing rain AND sleet. Southern areas run the highest risk for pure rain ending as snow. In the middle (where Louisville lies) ....it remains unclear.

It will be another sunny but chilly day for us. I adjusted temperatures up a bit with the colder air waiting a few hours longer to move in from the north. At least we get the sunshine today, but with clear skies tonight, temperatures will drop fast.

We will get a clear night this evening for a look at the International Space Station. It will only be visible for a couple minutes, which is probably as long as you would want to stand outside in this cold weather.

As we take a look ahead in the forecast... we have a potential ice and sleet event for Sunday night into Monday morning. Although this could change, right now it looks likely. Freezing rain occurs when there is a shallow layer of cold air near the ground. The precipitation falls as rain, then freezes once it hits the ground. If the layer of cold air is a bit thicker, the precipitation will be sleet instead of freezing rain. We have the potential for both Sunday night and Monday morning. This could make for a dangerous Monday morning commute and power outages.

February 26, 2014

Well, let's get right to it since I am sure you want an update on the Sunday event.

BUT---before that. I did want to mention Friday night's event.

This looks pretty minor at this point.

Our Futurecast shows the wave of moisture passing through Friday night. Profiles support rain or a mix of rain/snow with a burst of snow north.

This looks quick hitting...and accumulations look minor at this stage. We will watch it of course, but right now I don't see much with this one.

So that leads us to the weekend.

Good signals showing up that we will warm up nicely on Saturday. 40s likely...with some 50s south.

The problem then kicks into play on Sunday. We have a develop low pressure to our south. At the same time, an Arctic front is sliding into the region. The path of the low is critical on precip amounts and how much intrusion the Arctic air will have to cut in underneath the warm air from the low to the south. This is a classic overrunning setup. Very common in our area. And with all the cases of such---the amount of warm air is always in question. We have had cases where the warm air is stronger than the models indicated---leading to pure rain. We have also (even recently) ran into a setup with the models were too warm and we ended up with more icing than expected.

We just cannot nail down these events with models only. We need good data to develop a strong forecast. That may take until Friday evening or Saturday morning when weather balloons really get into this system to verify the model trends at that point. So between now and there...all we can do is advise about the setup and give our thoughts----but I highly caution detailed forecasts this far out.

Instead of posting the model images...I decide to give the overall setup we are facing.

There appears to be 2 trends developing in the models regarding the low track and depth of cold air.

TRACK 1--- takes the low more north across TN and SE KY. This would bring heavy rain at times into KY. Even some thunder. The freezing rain threat would be mainly north of Louisville and impacts IN/OH with heavy snow north of that (but for some reason the graphic didn't display that..ha)

TRACK 2-- takes the surface low more southerly. This still would allow decent moisture, but the amount of shallow Arctic air would be able to cut more underneath the warm layer. This would allow for more of a ice threat with heavy snow perhaps impacting our northern most counties.

With both track ideas----this system would end as a brief period of snow before ending. And very cold air follows.

There is a huge difference in heavy rain and an ice storm obviously. Public reaction to one over the other is huge as well...so that is why I say caution is needed in the forecast.

And I know some weather fans have access to model data and see the risk for up to 2" of ice. But keep in mind, the atmosphere has many layers...and the temperature of each layer can play a huge role in the type.

For example...here is the BUFKIT sounding from the GFS for this event in Louisville.

You read this right to left in time.

Green= rain Red= freezing rain Orange= sleet Blue= snow

You can see that this may not be entirely freezing rain. If we can get the cold layer deep enough in the lower levels, we may see this go to sleet. That would cut down on the ice accumulations. The above graphic shows the potential amount of freezing rain.

Yes, that is significant, but we can get either the colder air to stay more at bay...you can get more rain. If we go colder than shown...more sleet or even snow. I think we can all agree that pretty much anything is better than freezing rain if we had an option.

But that is just one model's idea. There are many out there. I just wanted to show you that we could see varying types at different stages of this event. So terms like "snowstorm" or "ice storm" shouldn't be used as a definite right now given the risk for the types to really switch up with this event.

We will look at it all again tomorrow and Friday. By that point, we should really see strong data to lean us in a good direction as far as expected types and amounts.

It looks interesting for the region for sure.

The cold that follows this storm is looking ...well...cold. We may be flirting with single digit lows or even below zero values again if we get anything frozen on the ground. Ugh.

The polar vortex is back for an unwelcomed visit. We only had a dusting of snow overnight, and now the bitter cold air is setting up in WAVE Country. It will at least be sunny today... but also cold and windy.

Here's a look at your hour by hour forecast with wind chill temperatures in light blue. It's going to be one of those sunglasses and winter coat kind of days.

We may get a rain/snow mix Friday night into Saturday morning, then a chance of rain with warmer temperatures on Saturday afternoon. This should not cause too many problems for us. Another round of wintry weather moves in Sunday night into Monday morning. This could cause some major problems for us because it has the potential for freezing rain and ice accumulation. This is something we will be watching closely for Sunday night because this could make Monday morning's drive to work icy and dangerous.

If you don't mind the chilly weather tonight, you can take a look at the ISS with the clear skies in the forecast.

Today will be another cool day, similar to yesterday, with highs in the lower 40s. But today will feel like a day on the beach compared to the dramatic temperature drop you'll feel by tomorrow morning as the Polar Vortex returns. In between now and tomorrow's brutally cold weather, we have yet another chance of snow.

Most of the snow will fall in off and on light snow showers between 10pm tonight through 5am tomorrow morning. This snow looks to be very light, so we don't expect much in the way of accumulation. This should only cause minor problems on the roads for tomorrow; however, since the temperatures will be so cold in the morning, we could have some icy spots on the roads (especially bridges and overpasses).

Here's the chances and timing of the snow. Most of the accumulation will occur from 12am-3am. Again, we are only expecting light accumulation, so this is not going to be a heavy snow.

Perhaps the bigger story for tomorrow is the return of the Polar Vortex. You'll be feeling the dramatic drop in temperatures first thing tomorrow morning as winds continue to gust. The frigid temperatures along with the blustery winds will bring wind chill temperatures down to the single digits... even near 0 degrees for many areas.

February 24, 2014

Lots of systems showing up on the maps the next couple of weeks...if not longer.

This is a pattern in which the southern jet stream is very active, and the northern branch is trying to supply cold air into the country at the same time. As with most of these cases, we have to look for any storm that can phase these 2 jets together to form a larger storm. As long as they stay separate, they will move quickly from west to east.

What does this mean for us? Well, when we face quicker systems...we usually have a better chance for snow locally. But mainly light. When they phase together into a bigger storm, when they phase becomes critical. If to our west, then it will be a warm/thunderstorm forecast for our area. If they phase over us or just to our east, more of a wintry threat...sometimes significant.

I highly urge caution for those model lovers out there that love to look at the longer term. With such an active pattern, you cannot get caught up on specifics of each system that moves through. Some of the "weak" ones you see down the road could easily become major storms once we get closer. The models do poorly with this.

So at this point, we do know that colder than normal is more likely than warmer than normal for quite some time. We do see several storm systems passing through...and each one will have a wintry component.

We will keep you updated on each one as we gain confidence.

For this blog update, I am going to focus on 4 that show up in our 7 day outlook.

1st-- Later Tonight--

Streak of light snow on the radar now will extend into IN and far NE KY later tonight. I would not rule out this impacting say Jackson/Jennings Counties in IN to about Carroll/Owen in KY. Very small accumulations possible with that band. The trend has been to keep it even futher north than that, but I just would not rule out some slight impacts for those counties. Kevin will have more on that on the 11p news especially tonight. For the rest of us---nothing.

2nd-- Late Tuesday evening/Early Wednesday

This one involves what I was mentioning above. A split setup of an Arctic front sliding in and a southern low pressure. Just about every model, including the one below (EURO) show these 2 as separate entities.

The Arctic front is expected to slide into the area late tomorrow night....react to the low developing in the Gulf of Mexico---and then light snow develops across KY. The debate seems to be with how much "development" will take place along that front.

GFS has a decent light coating.

NAM says it will be limited south.

There will be some dry air to overcome Tuesday afternoon based on the soundings I have looked at. So even once the snow breaks out...it initially may not hit the ground until we can saturate.

But we are dealing with an Arctic front and I have seen these break out some decent bands in the past. So I think keeping a light snow chance in the forecast is wise at this point. Based on the timing, KY runs a better chance of snow than IN. Snow ratios look to be about 15:1 (15" of snow to 1" of liquid). Model moisture amounts are roughly .5". The ratios can easily push that to 1" or perhaps a bit more in spots. So yes, a light snow event, but it may cross into advisory land if amounts more of 1" look more probable. Timing looks best between 10pm Tuesday Evening- 3am Wednesday morning. With temps in the teens overnight---slick spots quite likely if you pick up snow.

Wednesday by the way does look quite cold with some areas not reaching the 20s with low 20s expected elsewhere (Louisville may hit 25 due to urban effect).

3rd-- Friday night/Saturday

This one looks to be a wave that has been trending more north as we get closer. It still looks like the rain/snow line will lie across KY for this one. The timing of Friday night may help produce more wintry weather but that rain/snow line will shift a bit more north Saturday once we get to daylight.

EURO:

Amounts wise... looks light. 1"-2" possible where all snow.

4th Sunday night- Monday

This one is the most interesting one of the 4. It is one that shows a more organized low pressure moving in. Of course, this means warmer air gets involved.

Here is the BUFKIT output showing what I am talking about. You read this right to left by the way. You can see the light snow on there as well from systems 2 and 3. But when you look at the 4th..you can see how precip types change. (orange is sleet/red is freezing rain/green is rain/blue is snow).

The EURO shows a VERY tight gradient with this.

The thick white line is the freezing mark line. It lies across southern IN with mid 50s pushing into our southern counties. You can see the problem there.

So are we going to forecast freezing rain Sunday night? Not yet. With temperature profiles like that...the margin of error for this to go to even all snow or thunderstorms and 60 degrees is there. In other words, we have very low confidence in the 4th system at this time. So why discuss it? That is what this blog is for...a behind-the-scenes discussion of our thoughts when we look at the data so that you can understand why we put the data we do on that 7 day graphic.

Early thoughts are just to put a "mix" for this one right now.

After this 7 day period...I do see even more storm systems that are similar to all of the above. March looks very busy for us...but we rarely have a quiet March around here.

Clouds move in later in the afternoon, but we will still see plenty of sunshine today. Unfortunately, temperatures stay well below normal for this time of year. Our normal high is 51°, but we only expect to get up to 40°.

Just what you wanted, right? MORE SNOW! It's back in the forecast for tomorrow night through the early morning hours on Wednesday. This will not be a heavy snow event, but it could cause some issues for the Wednesday morning commute. Here are your chances of snow Tuesday night through Wednesday morning.

The accumulation looks to be very light. Around a half inch (if that) in Louisville. The duration of the snow will be longer just to the south of Louisville, so it's not out of the question to pick up close to an inch around Etown, Bardstown, Brandenburg and Willisburg.

Snow has not been in short supply this winter. We are getting close to doubling our expected snow totals for an entire winter season... and winter is not over yet.